Heat transfer apparatus with a variable absorption surface

ABSTRACT

Heat transfer apparatus with a variable absorption surface The heat transfer apparatus comprises a variable absorption surface ( 20 ) interposed between a transparent wall ( 12 ) and an insulating module ( 14 ), said variable absorption surface ( 20 ) being exposed to solar radiation through the transparent wall ( 12 ) and having absorbent regions ( 20 A) and reflective regions ( 20 R), as well as movable shutters ( 22 ) arranged opposite the variable absorption surface ( 20 ) and each having an absorbent side ( 22 A) and/or a reflective side ( 22 R), these shutters being movable between at least one first position and a second position so as to vary the absorbent regions and/or the reflective regions as well as the absorbent sides and/or the reflective sides exposed to solar radiation. The invention applies to the construction sector.

The invention relates to a heat transfer apparatus comprising a transparent wall in contact with a first thermal mass and adapted to be exposed to solar radiation, an insulating module placed between the transparent wall and a second thermal mass which is to be heated or cooled, the insulating module comprising circulation passages for a heat-carrying fluid which does or does not permit heat transfer between the first and second thermal mass.

Heat transfer apparatus of this kind are known particularly from EP 1060353 and EP 1216388 in the name of the present applicant.

These known devices are used in particular for transferring heat between a transparent wall exposed to solar radiation and another wall, such as for example a wall or roof of a building, a water reservoir, etc. In this case, the first thermal mass is the ambient outside air whereas the other thermal mass is the building, the reservoir, etc.

Heat transfer apparatus of this kind have the advantage of being able not only to transfer heat from solar radiation to the second thermal mass but also to prevent heat transfer in the opposite direction when the solar radiation has ceased. In other words, in this latter situation, this device behaves as an insulator preventing heat transfer from the second thermal mass which has been heated to the first thermal mass which is then at a lower temperature.

In EP 1 060 353, the insulating module comprises circulation passages for a heat-carrying fluid, usually air, that permit forced circulation using a fan.

In EP 1 216 388, the circulation passages allow circulating of the heat-carrying fluid by natural convection without the need for a fan or the like.

The invention sets out to improve still further the operation of heat transfer apparatus of this kind, both in the situation of heat transfer from the first thermal mass to the second thermal mass and in the situation where the second thermal mass has to be insulated to prevent heat transfer from this second thermal mass to the first thermal mass.

To this end, the invention proposes a heat transfer apparatus of the type defined hereinbefore, which comprises a variable absorption surface interposed between the transparent wall and the insulating module, said variable absorption surface being exposed to solar radiation through the transparent wall and having absorbent regions and/or reflective regions, as well as movable shutters arranged opposite the variable absorption surface and each having an absorbent side and/or a reflective side, these shutters being movable between at least a first position and a second position in order to vary the absorbent regions and/or the reflective regions and the absorbent sides and/or the reflective sides which are exposed to the solar radiation.

Thus, depending on the position of the movable shutters, the whole structure formed by the variable absorption surface and by the movable shutters presents a surface exposed to solar radiation which is either totally absorbent or totally reflective or both absorbent and reflective at the same time.

In the first case the whole structure absorbs solar radiation owing to the fact that both the absorbent regions of the variable absorption surface and the absorbent sides of the shutters are exposed simultaneously.

In the second case, the whole structure presents a reflective surface owing to the fact that reflective regions of the variable absorption surface and reflective sides of the shutters are exposed at the same time.

In the third case, the whole structure presents a surface which is both absorbent and reflective owing to the fact that both absorbent and reflective regions of the variable absorption surface and absorbent and reflective sides of the shutters are exposed at the same time. A mixed solution of this kind may be useful for installing the device in certain countries depending on the climatic conditions prevailing there.

As a result, in the first position (absorbent position) the variable absorption surface behaves as an absorber for solar radiation, whereas in the second position (reflective position) this surface behaves as a reflective surface.

In a preferred embodiment, the variable absorption surface has absorbent regions alternating with reflective regions, whereas the movable shutters each have an absorbent side and a reflective side opposite one another, these shutters being movable between a first position, known as the absorbent position, in which the absorbent sides of the shutters and the absorbent regions of the variable absorption surface are exposed and a second position, known as the reflective position, in which the respective reflective sides of the shutters and the reflective regions of the variable absorption surface are exposed.

It is advantageous that, in the first position, the reflective sides of the shutters come to be opposite the reflective regions of the variable absorption surface in order to obscure them, whereas, in the second position, the absorbent sides of the shutters come to be opposite the absorbent regions of the variable absorption surface in order to obscure them.

Although different configurations are possible, it is advantageous if the absorbent regions and the reflective regions of the variable absorption surface are constructed in the form of parallel strips of selected width extending in a main direction, for example vertical or horizontal, and the movable shutters are mounted to be pivotable about respective axes parallel to the main direction.

In an advantageous embodiment, the shutters are adapted so that they each pivot through substantially 180° from the first position to the second position, or vice versa, so that in the first position each shutter comes to obscure a reflective region of the variable absorption surface and, in the second position, each shutter comes to obscure an absorbent region immediately adjacent to said reflective region.

The adjective “absorbent” is intended to denote a region of the variable absorption surface or a side of a shutter which is capable of absorbing solar radiation by properties analogous to those of black bodies.

By contrast, the adjective “reflective” is intended to mean a region of the variable absorption surface or a side of a shutter that reflects or bounces back solar radiation so as not to absorb this radiation.

Preferably, the absorbent regions of the variable absorption surface and the absorbent sides of the shutters are dark in colour, more particularly black, whereas the reflective regions of the variable absorption surface and the reflective sides of the shutters are light in colour, more particularly white.

Of course, the invention is not limited to the use of a dark colour or a light colour in order to define an absorbent property or a reflective property, respectively.

The movable shutters may be mounted to be pivotable, as mentioned above, but they may also move in some other way, particularly by sliding or translation. In this case they will have only one side exposed to solar radiation which is either absorbent or reflective.

In the detailed description that follows, which is provided solely by way of example, reference is made to the attached drawings wherein:

FIG. 1 is a partial sectional view of a heat transfer apparatus according to the invention wherein the shutters are in a first position, in this case an absorbent position;

FIG. 2 is a view analogous to FIG. 1 in which the shutters are in an intermediate position;

FIG. 3 is a view analogous to FIGS. 1 and 2 wherein the shutters are in a second position, in this case a reflective position;

FIG. 4 is a partial front view of a heat transfer apparatus according to a first embodiment of the invention, wherein the shutters are shown in the absorbent position;

FIG. 5 is a sectional view along the line V-V in FIG. 4;

FIG. 6 is a sectional view along the line VI-VI in FIG. 4;

FIG. 7 is a sectional view along the line VII-VII in FIG. 4;

FIG. 8 is a view analogous to FIG. 4 in which the shutters are in a reflective position;

FIG. 9 is a sectional view along the line IX-IX in FIG. 8;

FIG. 10 is a sectional view along the line X-X in FIG. 8;

FIG. 11 is a sectional view along the line XI-XI in FIG. 8;

FIG. 12 is a partial sectional view through a heat transfer apparatus according to a second embodiment of the invention, which is installed underneath a sloping roof;

FIG. 13 is a partial sectional view through a heat transfer apparatus according to a third embodiment of the invention, analogous to that shown in FIG. 12, wherein the heat transfer apparatus is installed underneath a flat roof;

FIG. 14 is a front view of a heat transfer apparatus according to a fourth embodiment of the invention;

FIG. 15 is a sectional view along the line XV-XV in FIG. 14;

FIG. 16 is a back view of the heat transfer apparatus of FIG. 14;

FIG. 17 is a sectional view along the line XVII-XVII in FIG. 14;

FIGS. 18A and 18B are schematic sectional views through an assembly formed by a variable absorption surface and shutters that are movable in translation into two respective shutter positions;

FIGS. 19A and 19B are views analogous to FIGS. 18A and 18B according to one alternative embodiment;

FIGS. 20A, 20B and 20C are diagrammatic sectional views through an assembly formed by a variable absorption surface and inclined shutters which are movable in translation into three respective shutter positions; and

FIGS. 21A, 21B and 21C are views analogous to FIGS. 20A, 20B and 20C in an alternative embodiment.

Reference will be made first of all to FIG. 1 which shows, in partial section, a heat transfer apparatus 10 according to the invention comprising a transparent wall 12 (made of mineral or organic glass, for example) in contact with a first thermal mass M₁, namely the outer ambient medium, and adapted to be exposed to solar radiation S.

An insulating module 14 is placed between the transparent wall and a second thermal mass M₂ that is to be heated or cooled, this second thermal mass being, for example, a part (wall or roof) of a building, etc, which is to be heated or cooled.

The insulating module 14 is advantageously made of mineral wool and comprises circulation passages 16, 18 for a heat-carrying fluid (usually air) which does or does not permit heat transfer between the first thermal mass M₁ and the second thermal mass M₂. Here, the circulation passages 16, 18 are indicated solely by their respective axes.

According to the invention the device further comprises a variable absorption surface 20 interposed between the transparent wall 12 and the insulating module 14. This surface 20 backs onto the insulating module 14 so as to be able to be exposed to the solar radiation S through the transparent wall 12. The surface 20 has absorbent regions 20A alternating with reflective regions 20R.

Movable shutters 22 each mounted to pivot about its respective axis 24 are arranged facing the variable absorption surface 20 in a space 26, referred to as the external space, which is defined between the surface 20 and the transparent wall 12. This external space is sufficiently wide to allow the shutters 22 to pivot (see FIG. 2). The external space 26 contains the heat-carrying fluid, i.e. in this case air.

In the embodiment shown, the absorbent regions 20A and the reflective regions 20R of the variable absorption surface 20 are constructed in the form of parallel strips of a selected width L (FIG. 2) extending in a selected main direction, for example the vertical or horizontal direction, and the movable shutters 22 are mounted so as to pivot about their respective axes 24, the latter being parallel to the selected direction. In the example shown, the absorbent regions 20A and the reflective regions 20R have the same width L which corresponds substantially to the width of each of the movable shutters.

The movable shutters 22 have an absorbent side 22A on one side, and a reflective side 22R on the opposite side. These shutters are movable between a first position, known as the absorbent position, as shown in FIG. 1, and a second position, known as the reflective position, as shown in FIG. 3.

In the first position, the absorbent sides 22A of the shutters and the absorbent regions 20A of the variable absorption surface are exposed at the same time. Thus, the surface 20 in conjunction with the shutters 22 forms an absorbent surface for solar radiation.

In the intermediate position shown in FIG. 2, the shutters have pivoted through substantially 90° relative to the position shown in FIG. 1.

In the position shown in FIG. 3, known as the reflective position, the shutters have pivoted through substantially 180° in relation to the position shown in FIG. 1. In this position, the reflective sides 22R of the shutters and the reflective regions 20R of the variable absorption surface 20 are exposed at the same time.

As can be seen from FIG. 1, in the first position, the reflective sides 22R of the shutters come to be opposite the reflective regions 20R of the variable absorption surface so as to obscure them. By contrast, in the second position (FIG. 3) the absorbent sides 22A of the shutters 22 come to be opposite the absorbent regions 20A of the variable absorption surface 20 in order to obscure them.

Thus, the shutters 22 are each capable of pivoting substantially through 180° from the first position (FIG. 1) to the second position (FIG. 3), or vice versa. In the first position, each shutter comes to obscure a reflective region 20R of the variable absorption surface. In the second position (FIG. 3) each shutter comes to obscure an absorbent region 20A immediately adjacent to said reflective region.

The absorbent regions 20A of the variable absorption surface 20 and the absorbent sides 22A of the shutters are advantageously dark in colour, particularly black. The absorbent regions 20A and the absorbent sides 22A are schematically shown in FIGS. 1 to 3 in the form of thin shaded zones to identify them.

The reflective regions 20R of the variable absorption surface 20 and the reflective sides 22R of the shutters are advantageously light in colour, particularly white. The reflective regions 20R and the reflective sides 22R are schematically shown in FIGS. 1 to 3 in the form of thin unshaded zones to identify them.

The absorbent regions and sides, like the reflective regions and sides, may be produced by any suitable means, particularly by painting, by applying a coating, etc.

The apparatus advantageously comprises a manually operated or motorized actuator 28 (FIG. 1) for moving the shutters 22 in synchronism.

Reference will now be made to FIGS. 4 to 7 to describe a first embodiment of a heat transfer apparatus according to the invention using a variable absorption surface 20 and shutters 22 as described previously.

The circulation passages passing through the insulating module 14 comprise first circulation channels 16 connecting the external space 26 for heat-carrying fluid and an internal space 30 for heat-carrying fluid disposed in contact with the second thermal mass M₂. The spaces 26 and 30 extend either side of the insulating block 14 in directions which are substantially parallel and vertical in the embodiment shown. The first circulation channels 16 open out into absorbent regions 20A of the variable absorption surface 20 and pass upwardly through the insulating module starting from the respective absorbent regions (see FIG. 5). Two vertically superimposed channels 16 open out into an absorbent region 20A in each case.

The circulation passages further comprise second circulation channels 18 which connect the external space 26 for heat-carrying fluid with the internal space 30 for heat-carrying fluid. These second circulation channels open out into reflective regions 20R of the variable absorption surface 20 and pass downwardly through the insulating module, starting from the reflective regions (FIG. 6). Two vertically superimposed channels 18 open into a reflective region 20R in each case.

In the absorbent position shown in FIGS. 4 to 7, the absorbent regions 20A of the variable absorption surface and the absorbent sides 22A of the movable shutters are exposed. These shutters come to uncover the channels 16 and block off the channels 18. Thus, in the absorbent position of the shutters, the first circulation channels 16 are open, while the second circulation channels are closed. As a result the heat-carrying fluid can circulate in a closed loop on each occasion, as indicated by the arrows in FIG. 5. Because the heat-carrying fluid is heated up in the space 26, it has a tendency to rise, making use of the upwardly directed channels 16 to transfer heat into the internal space 30 by natural circulation.

The method of operation here is similar to that described in the publication EP 1216388 mentioned previously. In the absence of solar radiation, when the space 26 is colder than the space 30 the fluid stops moving and the module 14 becomes a heat insulator. This operation is particularly useful in winter to transfer heat to the second thermal mass M₂ which may be a wall of a building, for example.

FIGS. 8 to 11 show the insulating module in the second position, i.e. in the reflective shutter position. In this position, only the reflective regions 20R of the surface 20 and the reflective sides 22R of the shutters are exposed. Moreover the first circulation channels 16 are closed off by the shutters, while the second circulation channels 18 are open. As a result it is only possible for air to circulate naturally in the different loops as shown in FIG. 10. This configuration is useful in summer, as the warmer air which is closer to the mass M₂, i.e. in the internal space 30, has a tendency to rise, making use of the channels 18 to travel towards the external space 26, thus transferring heat from the second thermal mass M₂ to the first thermal mass M₁. Here again, the circulation principle is similar to that described in the publication EP 1216388 mentioned previously.

In the embodiment shown in FIGS. 5 to 11, the second thermal mass M₂ is advantageously a generally vertical wall of a building, for example an external wall. The apparatus 10 is in this case arranged in a generally vertical direction against the wall of the building, while the transparent wall 12 and the insulating module 14 also extend in this vertical direction.

In the embodiment shown in FIGS. 5 to 11, the insulating module is advantageously formed from a mineral wool, for example rockwool, and the circulation channels 16 and 18 are advantageously drilled directly into the thickness of the insulating module to pass right through it and terminate in the external space 26 and internal space 30.

In the embodiment shown, the absorbent regions 20A and the reflective regions 20R of the surface 20 are constructed in the form of narrow parallel strips. In the absorbent regions 20A, two superimposed channels 16 terminate in each case, whereas in the reflective regions 20R, two superimposed channels 18 terminate at the same time.

Reference will now be made to FIG. 12 which shows the use of a heat transfer apparatus according to the invention in the case of a sloping roof T. The second thermal mass M₂ is in this case an internal wall 32 arranged under the roof and forming, for example, a ceiling structure for a room inside the building.

The transparent wall 12 of the heat transfer apparatus 10 is provided so as to be integrated in the slope of the roof, while the insulating module 14 is adapted to extend in a generally vertical direction, being arranged in each case between the transparent wall 12 and the internal wall 32. In the embodiment, a plurality of insulating modules 14 may be provided, spaced from one another. Each of the insulating modules comprises, as in the previous embodiment, circulation channels 16 directed upwards from the variable absorption surface 20 to the opposite side. The module further comprises downwardly directed channels 18.

Opposite the variable absorption surface 20 are arranged a plurality of movable shutters 22 which are schematically shown here. The solar radiation S that passes through the transparent wall 12 heats the heat-carrying fluid, in this case air, contained in an external space 26, which communicates with an internal space 30 through the above mentioned channels. In each case, this internal space 30 is bounded by a heat conducting element 34 arranged in a substantially vertical position and connected in thermal contact with the internal wall 32. This heat conducting element may be, for example a heat conducting fin.

Moreover, the space 26 is bounded by an insulating block 36 backing onto an adjacent heat conducting element 34 and bounding a concave wall 38 which helps to send the solar radiation S towards the variable absorption surface 20.

The heat transfer apparatus in FIG. 12 operates analogously to that in the previous embodiment.

Reference will now be made to FIG. 13 which shows a heat transfer apparatus analogous to that in FIG. 12, except that the roof T is a flat roof in this case. As a result, the transparent wall 12, and the internal wall 32, are substantially horizontal. As in the previous embodiment, the insulating modules 14 are implanted vertically, like the heat conducting elements 34.

In the previous embodiments, the circulation of the heat-carrying fluid, generally air, is carried out by natural convection.

Reference will now be made to FIGS. 14 to 17 which show another embodiment of the invention using the principle of heat transfer described in the publication EP 1060353 mentioned above, and which operates with forced circulation of the heat-carrying fluid.

The heat transfer apparatus in FIGS. 14 to 17 comprises an insulating module 14 that forms a separation between an external space 26 bounded by the transparent wall 12, which is in contact with a first thermal mass M₁ and an internal space 30 bounded by the second thermal mass M₂ which is to be heated.

The circulation passages comprise two openings 40 and 42 which pass right through the insulating module and are located at the same height but offset in the widthways direction. One of these two openings, namely the opening 42, is provided with a controlled operation fan 44 to provide forced circulation of the heat-carrying fluid between the external space 26 and the internal space 30 or vice versa.

The internal space 26 is delimited over part of its height by a vertically directed partial partition 46, whereas the internal space 30 is also delimited, over part of its height, by a partial partition 48. This makes it possible to define on each occasion a U-shaped circulation pathway for the heat-carrying fluid as shown by the arrows in FIGS. 14 and 16.

As in the apparatus according to the publication EP 1060353, the fan is capable of being put into at least one of the following states, as selected:

an open state (fan operating) which allows air to circulate between the external space and the internal space and thus permits heat transfer between the thermal mass M₁ and the thermal mass M₂, and

a closed state (fan stopped) which prevents air from circulating between the external space 26 and the internal space 30 and thus prevents a heat transfer between the thermal masses M₁ and M₂.

As can be seen from the sectional views in FIGS. 15 and 17, the transfer apparatus also comprises, in front of the insulating module, a variable absorption surface 20 adapted to receive solar radiation S that has passed through the transparent wall 12. In front of this surface 20 are arranged shutters 22 analogous to those described herein before and capable of being moved from one to the other of two positions, comprising an absorbent position and a reflective position. In the embodiment the shutters are mounted to be pivotable about their respective vertical axes.

In the embodiment shown in FIGS. 18A and 18B, the variable absorption surface 120 has absorbent regions 120A alternating with reflective regions 120R. These regions 120A and 120R are analogous to the regions 20A and 20B described above and are constructed in the form of vertical parallel strips. The movable shutters 122 each have a reflective surface 122R and are movable in translation between a first position (FIG. 18A) in which the reflective surfaces 122R of the shutters 122 and the reflective regions 120R of the variable absorption surface 120 are exposed and a second position (FIG. 18B) in which the reflective sides 122R of the shutters 122 and the absorbent regions 120A of the variable absorption surface 120 are exposed.

Thus, the assembly formed by the surface 120 and the shutters 122 is 100% reflective in the position shown in FIG. 18A, and 50% absorbent and 50% reflective in the position shown in FIG. 18B. The shutters 122 have substantially the same width as the regions 120A and 120B and are jointly movable in translation in a direction D parallel to the plane of the surface 120. This translational movement is carried out by means of an actuator (not shown) which performs a sliding movement. Each shutter has only one reflective side 122R which is permanently exposed to solar radiation.

The alternative embodiment in FIGS. 19A and 19B is similar to those in FIGS. 18A and 18B, except that each shutter has only one absorbent side 122A which is permanently exposed to the solar radiation. The variable absorption surface 120 has absorbent regions 120A alternating with reflective regions 120R. The movable shutters 122 are movable in translation between a first position in which the absorbent side 122A of the shutters 122 and the reflective regions 120R of the variable absorption surface 120 are exposed (FIG. 19A) and a second position in which the absorbent sides 122A of the shutters 122 and the absorbent regions 120A of the variable absorption surface 120 are exposed.

Thus, the assembly formed by the surface 120 and the shutters 122 is 50% absorbent and 50% reflective in the position shown in FIG. 19A and 100% absorbent in the position shown in FIG. 19B.

The embodiments shown in FIGS. 18A and 18B and FIGS. 19A and 19B are suitable for insulating modules having either passages for the natural circulation of the heat-carrying fluid, as described previously with reference to FIGS. 4 to 13, or passages for forced circulation as described previously with reference to FIGS. 14 to 17.

In the embodiment shown in FIGS. 20A to 20C, the variable absorption surface 220 has absorbent regions 220A spaced in pairs and arranged obliquely with respect to a direction D which is parallel to the plane of the surface 20. Each of the absorbent regions 220A forms an acute angle with the surface 220 to which it is attached, the whole assembly being formed for example from soldered sheet metal.

The movable shutters 222 are arranged obliquely and each have a reflective side 222R and are movable in translation in the direction D between a first position (FIG. 20A) in which the absorbent regions 220A of the variable absorption surface 220 are exposed and a second position (FIG. 20C) in which the reflective sides 222R of the shutters 222 are exposed.

The shutters 222 are attached to a common support (not shown) which slides in the direction D and each form the same angle with this direction. The assembly thus formed is 100% absorbent in the position shown in FIG. 20A and 100% reflective in the position shown in FIG. 20C. FIG. 20B shows an intermediate position which in principle has no functional role.

In the alternative embodiment shown in FIGS. 21A to 21C the surface 220 has reflective regions 220R spaced in pairs and arranged obliquely with respect to the selected direction D. The movable shutters 222 are arranged obliquely and each have an absorbent side 222R. They are movable in translation in the direction D between a first position (FIG. 21A) in which the reflective regions 220R of the variable absorption surface 220 are exposed and a second position (FIG. 21C) in which the absorbent sides 222A of the shutters 222 are exposed. FIG. 21B shows an intermediate position which in principle has no functional role. The assembly thus formed is 100% reflective in the position shown in FIG. 21A and 100% absorbent in the position shown in FIG. 21C.

The embodiments of FIGS. 20A and 20B and of FIGS. 21A and 21B are chiefly suitable for an insulating module having passages for the forced circulation of heat-carrying fluid as described previously with reference to FIGS. 14 to 17.

The invention is capable of numerous alternative embodiments and is not limited to the particular embodiments described hereinbefore.

Thus the movable shutters may be made to pivot or slide and their orientation may be vertical or horizontal.

The apparatus according to the invention may be in the form of a modular element ready for installation and having selected dimensions, for example a rectangular element measuring 0.60 m by 1.00 m, these dimensions being given purely as a guide.

The invention has general applications in the field of construction, particularly for heating premises in cold weather and cooling premises in hot weather. 

1. Heat transfer apparatus, comprising a transparent wall (12) in contact with a first thermal mass (M₁) and adapted to be exposed to solar radiation (S), an insulating module (14) placed between the transparent wall (12) and a second thermal mass (M₂) which is to be heated or cooled, the insulating module (14) comprising circulation passages (16, 18) for a heat-carrying fluid which does or not permit heat transfer between the first thermal mass (M₁) and the second thermal mass (M₂), characterized in that it comprises a surface with variable absorption (20; 120; 220) interposed between the transparent wall (12) and the insulating module (14), said variable absorption surface being exposed to solar radiation (S) through the transparent wall (12) and having absorbent regions (20A; 120A; 220A) and/or reflective regions (20R; 120R; 220R), as well as movable shutters (22; 122; 222) arranged opposite the variable absorption surface (20; 120; 220) and each having an absorbent side (22A; 122A; 222A) and/or a reflective surface (22R; 122R; 222R), these shutters being movable between at least one first position and a second position in order to vary the absorbent regions and/or the reflective regions as well as the absorbent sides and/or the reflective sides exposed to the solar radiation.
 2. Heat transfer apparatus according to claim 1, characterized in that the variable absorption surface (20) has absorbent regions (20A) alternating with reflective regions (20R), in that the movable shutters (22) each have an absorbent side (22A) and a reflective side (22R) opposite one another, these shutters being movable between a first position, known as the absorbent position, in which the absorbent sides (22A) of the shutters (22) and the absorbent regions (20A) of the variable absorption surface (20) are exposed and a second position, known as the reflective position, in which the respective reflective sides (22R) of the shutters (22) and the reflective regions (20R) of the variable absorption surface (20) are exposed.
 3. Heat transfer apparatus according to claim 2, characterized in that, in the first position, the reflective sides (22R) of the shutters (22) come to be opposite the reflective regions (20R) of the variable absorption surface (20) in order to hide them, whereas in the second position the absorbent sides (22A) of the shutters (22) come to be opposite the absorbent regions (20A) of the variable absorption surface (20) in order to hide them.
 4. Heat transfer apparatus according to one of claims 2 and 3, characterized in that the absorbent regions (20A) and the reflective regions (20R) of the variable absorption surface (20) are constructed in the form of parallel strips of a selected width (L) extending in a selected main direction, and in that the movable shutters (22) are mounted to be pivotable about respective axes (24) parallel to the selected main direction.
 5. Heat transfer apparatus according to claim 4, characterized in that the movable shutters (22) are each capable of pivoting through substantially 180° from the first position to the second position, or vice versa, so that in the first position each shutter (22) comes to hide a reflective region (20R) of the variable absorption surface (20) and, in the second position, each shutter (22) comes to hide an absorbent region (20A) immediately adjacent to said reflective region (20R).
 6. Heat transfer apparatus according to claim 1, characterized in that the variable absorption surface (120) has absorbent regions (120A) alternating with reflective regions (120R), in that the movable shutters (122) each have a reflective side (122R) and are movable in translation between a first position in which the reflective sides (122R) of the shutters (122) and the reflective regions (120R) of the variable absorption surface (120) are exposed and a second position in which the reflective sides (122R) of the shutters (122) and the absorbent regions (120A) of the variable absorption surface (120) are exposed.
 7. Heat transfer apparatus according to claim 1, characterized in that the variable absorption surface (120) has absorbent regions (120A) alternating with reflective regions (120R), in that the movable shutters (122) each have an absorbent side (122A) and are movable in translation between a first position in which the absorbent sides (122A) of the shutters (122) and the reflective regions (120R) of the variable absorption surface (120) are exposed and a second position in which the absorbent sides (122A) of the shutters (122) and the absorbent regions (120A) of the variable absorption surface (120) are exposed.
 8. Heat transfer apparatus according to claim 1, characterized in that the variable absorption surface (220) has absorbent regions (220A) spaced in pairs and arranged obliquely relative to a selected direction (D) and in that the movable shutters (222) are arranged obliquely and each have a reflective surface (222R) and are movable in translation in said given direction (D) between a first position in which the absorbent regions (220A) of the variable absorption surface (220) are exposed and a second position in which the reflective sides (222R) of the shutters (222) are exposed.
 9. Heat transfer apparatus according to claim 1, characterized in that the variable absorption surface (220) has reflective regions (220R) spaced in pairs and arranged obliquely with respect to a selected direction (D) and in that the movable shutters (222) are arranged obliquely and each have an absorbent side (222R) and are movable in translation in said given direction (D) between a first position in which the reflective regions (220R) of the variable absorption surface (220) are exposed and a second position in which the absorbent sides (220A) of the shutters (222) are exposed.
 10. Heat transfer apparatus according to one of claims 1 to 9, characterized in that the absorbent regions (20A; 120A; 220A) of the variable absorption surface (20; 120; 220) and the absorbent sides (22A; 122A; 222A) of the shutters (22; 122; 222) are dark in colour, particularly black, while the reflective regions (20R; 120R; 220R) of the variable absorption surface (20; 120; 220) and the reflective sides (22R; 122R; 222R) of the shutters (22; 122; 222) are light in colour, particularly white.
 11. Heat transfer apparatus according to one of claims 1 to 10, characterized in that it comprises an actuator (28) for moving the shutters (22; 122; 222) in synchronism.
 12. Heat transfer apparatus according to one of claims 1 to 11, characterized in that the circulation passages (16, 18) for the insulating module (14) allow natural circulation of the heat-carrying fluid.
 13. Heat transfer apparatus according to claim 12, characterized in that the circulation passages comprise: first circulation channels (16) connecting an external space (26) for heat-carrying fluid located between the transparent wall (12) and the variable absorption surface (20; 120) and an internal space (30) for heat-carrying fluid arranged in contact with the second thermal mass (M₂), these first circulation channels terminating in absorbent regions (20A; 120A) of the variable absorption surface and passing upwardly through the insulating module (14) from the absorbent regions; and second circulation channels (18) connecting the external space (26) for heat-carrying fluid and the internal space (30) for heat-carrying fluid, these second circulation channels terminating in reflective regions (20R; 120R) of the variable absorption surface (20; 120) and passing downwardly through the insulating module (14) from the reflective regions; so that, in an absorbent position of the shutters, the first circulation channels (16) are open, while the second circulation channels (18) are closed and that, in a reflective position of the shutters, the first circulation channels (16) are closed, while the second circulation channels (18) are open.
 14. Heat transfer apparatus according to claim 13, characterized in that: in the absorbent position of the shutters, natural circulation of the heat-carrying fluid takes place only if the temperature of the heat-carrying fluid in the external space (26) is greater than the temperature of the heat-carrying fluid in the internal space (30), thus permitting heat transfer from the external space to the internal space, and in the reflective position of the shutters, natural circulation of the heat-carrying fluid takes place only if the temperature of the heat-carrying fluid in the external space (26) is below the temperature of the heat-carrying fluid in the internal space (30), thus permitting heat transfer from the internal space to the external space.
 15. Heat transfer apparatus according to one of claims 1 to 14, wherein the second thermal mass (M₂) is a generally vertical wall of a building, characterized in that said transfer apparatus (10) is arranged in a generally vertical direction along the wall of the building, the transparent wall (12) and the insulating module (14) extending in said direction.
 16. Heat transfer apparatus according to one of claims 1 to 14, wherein the second thermal mass (M₂) is an internal wall (32) arranged below a roof (T) with a selected slope, characterized in that the transparent wall (12) of the apparatus is provided so as to integrate in the slope of the roof, while the insulating module (14) is adapted to extend in a generally vertical direction.
 17. Heat transfer apparatus according to claim 16, characterized in that it comprises at least one heat conducting element (34) connected in heat contact with the internal wall (32) and arranged along the insulating module (14) opposite the variable absorption surface (20).
 18. Heat transfer apparatus according to one of claims 1 to 11, characterized in that the circulation passages (40, 42) of the insulating module (14) permit forced circulation of the heat-carrying fluid.
 19. Heat transfer apparatus according to claim 18, characterized in that the circulation passages comprise two openings (40, 42) passing through the insulating module (14), one of which (42) is provided with a controlled-operation fan (44), and provides communication between an external space (26) located between the transparent wall (12) and the variable absorption surface (20) and defining a U shaped circulation pathway for the heat-carrying fluid, and an internal space (30) arranged in contact with the second thermal mass (M₂) and defining a U-shaped circulation pathway for the heat-carrying fluid, the fan (44) being capable of being put selectively into at least one of the following states: an open state that allows heat-carrying fluid to circulate between the external space (26) and the internal space (30) and thus permits heat transfer between the first thermal mass (M₁) and the second thermal mass (M₂); and a closed state that prevents heat-carrying fluid from circulating between the external space (26) and the internal space (30) and thus prevents heat transfer between the first thermal mass (M₁) and the second thermal mass (M₂).
 20. Heat transfer apparatus according to one of claims 1 to 19, characterized in that the heat-carrying fluid is air. 